To casual YouTube viewers, the swarms of Asian carp filmed jumping in the Mississippi River may represent entertainment. To biologists, they represent an invasive species.

Asian carp were brought to the river in hopes that they would help solve a problem with invasive aquatic weeds. Instead, they became an invasive species themselves, breeding out of control because they had no natural predators in the area. Now, boating is unsafe in parts of the Mississippi, because the fish — which can weigh up to 100 pounds, according to the EPA — leap out of the water and hit people. Asian carp also disrupt the food chain that supports fish native to the river.

But not all invasive species are so obvious that they jump up and hit people in the face. On his way into Eugene to give a presentation for the Science Pub series at Luna, OSU professor Sam Chan stopped to walk around in a residential area near 7th Ave. and Chambers Street. Within 20 minutes, he was able to collect two five-gallon buckets, plus a smaller glass jar, full of invasive plants — and that’s including time he spent knocking on doors and asking permission to take plants.

Many plants are intentionally brought from one place to another for various utilitarian or ornamental purposes. For example, the hops used to make the beer some Science Pub attendees were drinking are an introduced species, Chan noted. And many plants not native to an area are able to exist there without causing significant disruption to the local ecosystem.

“We don’t really have a good mechanism for being able to screen which ones will be invasive,” said Chan, an aquatic invasive species specialist with the Oregon Sea Grant Extension at OSU.

Some general characteristics of invasive species include the ability to tolerate a wide variety of environments and a tendency to congregate in groups. The Oregon Invasive Species Council provides a list of invasive species that are particularly a problem in Oregon (www.oregon.gov/OISC/most_dangerous.shtml).Invasive species include animals as well as plants. Pets can become invasive species if they escape or are abandoned by their owners. Even dumping fish into waterways they did not come from is potentially harmful although it is commonly done. Chan said that a colleague of his was recently shocked to receive an invitation to a “release party” where a local school was going to release some non-native crayfish they had been studying into Amazon Creek.

An audience member asked Chan whether European settlers were an invasive species. In deliberating his answer, Chan considered that while humans can cause harm to the environment, they are unique in their ability to solve problems.

“Are humans an invasive species? Yeah,” he finally answered.

The result of invasive species allowed to proliferate unchecked is an environment where only species that are very resistant to human disruption thrive, Chan said. Human disruptions to the environment also contribute to the spread of invasive species. For instance, Devil’s Lake in Lincoln City had problems with aquatic weeds, so non-native fish were brought in. This didn’t address the cause of the weed problem, which was that the weeds were getting fertilized by the leaking septic tanks of houses surrounding the lake, so instead of having a weed problem, the lake came to have a problem with toxic blue-green algae.

Ecosystems change naturally over time as a result of various natural disruptions. For instance, before the volcano Mount Mazama blew and created Crater Lake, the dominant trees in the area were Oregon ash. Afterwards, alder trees and Douglas fir became more prominent.

Therefore, the goal of dealing with invasive plants is not to restore the habitat to what it was at a certain point in the past, but to find out “what is best suited for the current environment and the ecology,” Chan said.

Chan said to combat the problem of invasive species, people should learn about invasive species and learn to recognize them, and they should share that information with people they know. Sightings of invasive species should also be reported to the Oregon invasive species hotline at 1-866-INVADER.

Chan also advised against disposing of invasive plants by simply uprooting them and putting them in the trash or yard waste disposal — that still leaves them capable of spreading seeds at their next destination. Instead, cut the plants up, let them dry out, and then put the pieces in the trash or in a compost heap, Chan said.

Chan’s presentation was part of the Science Pub series, which is sponsored by the Oregon Museum of Science and Industry (OMSI), the UO’s College of Arts and Sciences, The Science Factory and Luna. These interactive presentations take place at 7 pm (come earlier to order food and drinks) on the second Thursday of every month at Luna, 30 E. Broadway.

Next month’s presentation, on Sept. 13, will be UO physics professor Jim Brau speaking on “Particles, Energy and Our Mysterious Universe.” October’s presentation will be about the solar system, and November’s presentation will discuss the research of OSU’s wave laboratory in relation to tsunamis.

Get Involved

These are some organizations in the Eugene area that work with issues related to invasive species.

• Walama Restoration Project (www.walamarestoration.org) works to rehabilitate waterways, forests and grasslands in and around the valley. The group also designs and presents instructional material about invasive species for schools and community education programs. They have internship and volunteer opportunities for seasonal projects, and they also rely on the financial support of members.

• Friends of Hendricks Park (www.friendsofhendrickspark.org) coordinates volunteer maintenance of the park in south Eugene. Volunteer work parties for the removal of ivy and invasive weeds are held one Saturday each month. The next is on Aug. 18, beginning at 9:30 am in the picnic shelter. Snacks and tools are provided; bring heavy shoes and work gloves.

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